Data link controller (DLCs) are used in integrated services digital networks (ISDNs) to provide a high-speed serial interface to a telecommunication network. Bit Oriented Protocols (BOPs) specify the data format employed in transmission over the network and call for transmission in "packets" complying with certain norms.
Typically, the status of individual characters with a packet is reported. This creates excessive overhead time in monitoring the reception of a packet. And during transmission excessive intra-packet intervention is required. Typically, packet boundaries were of no significance.
The limitations meant that complex programming requirements are imposed on a DLC user and moreover, throughput of the DLC is compromised because of the excessive processor time required in the character-by-character method of reception and transmission of data.